In a retrospective study 56 consecutive patients with uveitis of unknown origin and 56 consecutive patients suffering from uveitis of established aetiology were investigated. The purpose of this study was to determine the frequency of positive serological tests for Lyme borreliosis among patients with uveitis and to relate laboratory data to clinical findings. The antibody titre for Borrelia burgdorferi was determined by two assays: the indirect immunofluorescence assay and the enzyme linked immunosorbent assay. A positive result according to one or both assays was found for eight patients with uveitis of unknown aetiology (14%) and three patients with uveitis of established cause (5%). On clinical examination, none of the patients fulfilled the CDC criteria for diagnosis of Lyme borreliosis.